1. FIELD OF THE INVENTION
This invention relates to hammers for driving nails and striking various objects and, in particular, shock-absorbing or dead blow hammers that reduce the recoil and vibration caused by the hammer strike. More particularly, the present invention relates to a shock-absorbing hammer including a claw feature.
2. DESCRIPTION OF RELATED ART
When a percussive tool, such as a hammer, strikes the surface of an object, part of the energy produced by the strike is used to perform desired work (e.g., drive a nail), part is converted into heat, and part is dissipated through the hammer. The energy that is dissipated through the hammer often produces undesirable results such as recoil of the hammer from the struck surface or excessive vibration of the hammer. The undesirable results produced by hammer strikes have been a persistent problem for the makers of hammers and other percussive tools.
Many users of hammers prefer the vibration-reducing feel of wood handled hammers, rather than integral steel handle/head hammers. A common perception is that fatigue is reduced at the end of the day when using a hammer having a wood handle verses a steel handle. However, wooden handled hammers will invariably break, typically at the wedged joint between the handle and steel head due to the prying action of nail pulling. To overcome this shortcoming, many manufacturers make integral steel handle/head hammers which hold up extremely well to nail pulling, but the shock absorbing feature of the wood handle is lost. These problems are discussed in an article entitled "Nailing Basics," by Larry Haun in Fine Homebuilding, Jul. 1997 at page 80.
In the past, various attempts have been made to reduce undesirable results produced by a hammer strike. Hammers that have minimal rebound or recoil characteristics are sometimes referred to as "dead blow" hammers. One of the earliest attempts reflected in the prior art to produce a dead-blow hammer is U.S. Pat. No. 1,045,145, issued in November 1912 to E.O. Hubbard ("Hubbard"). As explained by Hubbard, when the Hubbard hammer is struck against a surface, the striking head will be forced against a cushion, such that the cushion absorbs a portion of the shock of impact produced by the strike.
Following Hubbard, several other attempts were made to reduce the undesirable results of a hammer strike and, in particular, to reduce the recoil or rebound produced when a hammer strike occurs. Several early approaches for reducing recoil in hammers are summarized in U.S. Pat. No. 2,604,914 to Kahlen ("Kahlen") issued in July 1952. In particular, Kahlen indicates that, by 1952, known methods for reducing hammer recoil included placing either a slug, a charge of round shot, or a charge of powdered material in a chamber immediately behind a striking face of the hammer, such that the object(s) placed behind the striking head will absorb some of the forces produced by the hammer strike. The particular approach disclosed in Kahlen involved the placement of a charge of irregularly-shaped, hard heavy particles in a chamber immediately behind the striking head of a hammer.
In addition to solutions involving cushions and charge loads, several solutions utilizing resilient members, such as elastic inserts and springs, were proposed to address the hammer strike problems, whereby a portion of the energy developed from the hammer strike is dissipated through the resilient member. Other designs, such as that disclosed in U.S. Pat. No. 5,408,902, use a "lagging mass," which is positioned to move towards the striking portion of the hammer head when it impacts, thus impacting the striking portion to reduce hammer recoil.
Theses early approaches suffer from one or more difficulties. For example, the use of slidable weights or slugs behind the striking head of the hammer is problematic because the weights themselves develop potential energy when the hammer strikes a surface and tend to recoil, thus, causing undesirable vibration or oscillation of the hammer. Further, shot-filled hammers are limited: (i) because the requirement for a hollow chamber renders the size of such hammers out of proportion to their weight; and (ii) because, unless a special shot mixture is utilized, the shot is often not useful in preventing hammer recoil. Moreover, in prior art dead blow hammers, the prying and nail pulling capability of common claw hammers has been forfeited in the attempts to reduce vibration and recoil.
Further discussion of the prior art and its associated shortcomings is provided in U.S. Pat. No. 1,045,145; U.S. Pat. No. 2,604,914; U.S. Pat. No. 2,928,444; U.S. Pat. No. 4,831,901; U.S. Pat. No. 5,118,117; U.S. Pat. No. 5,408,902; and German Patent No. 1,273,449.
Thus, a need exists for a shock-absorbing hammer which includes a claw feature for pulling nails and prying, and that addresses other problems associated with prior art shock-absorbing or dead blow hammers.